One idea I had was to turn a small fiberglass camper into a roomy bathroom for a group of campers for use at a site without facilities. So it could be just like you would have at home--a full size shower and bathtub, or even a jacuzzi, along with the normal toilet and sink wash station.

So we need a way to get water, dispose of gray water, and dispose of black water.

Water fill pumps, hoses, and filters could be used to take on water at a lakeside for example. So there is no need to carry water. We just need a big tank.

I know very little about RV toilets, but a fair amount about Marine Heads. I was wondering if anyone has used a Marine head in an RV? Some examples would be an Electrosan head which incinerates the waste--nice when you have shore power hooked up or if you have a generator and power to spare, or Vacuflush which used a reduced amount of water to flush--about 1/3--compared to a typical marine head, and features high quality porcelain bowls.

The Electrosan has a heating element and leaves a powdery residue which I'd think could disposed of by being buried. In the marine world this cannot be disposed of by dumping, even though there is zero bacteria. Many feel there is no reason why this could not be dumped in an environmentally conscious manner. On shore it is no different from campfire ashes. So that eliminates black water.

I would think that gray water which is used wash water--water plus soap and a little dirt. Can not gray water be treated to remove the soap or whatever and be discharged harmlessly?

So the final requirement is power. A bank of solar panels and a couple of wind generators, coupled with a generator and batteries, would provide the power.

It would be interesting to run the numbers on power needed to run an Electrosan head, and determine the cost per person to operate such a system.

The bottom line is it is possible to build a system that only requires power to operate in an environmentally harmless way, but the penalty would be cost and weight, and power consumption.

As far as replenishing fresh water, we use a water bladder that holds 45 gallons. It lays in the truck bed to fill at the closest facility and transport home, and we pump the water into the fresh water tank using our water pump by reversing a valve. The bladder looks rather like a water bed mattress, but very small. I think we bought it from Camping World.

Recycling grey water is done in some homes; haven't seen it in trailers. Most systems just use the grey for toilet flushing and watering the lawn, but some are more extensively filtered. This could be the trickiest part of the bathroom trailer. Otherwise, you're probably stuck with a lot of blue boy action...

One idea I had was to turn a small fiberglass camper into a roomy bathroom for a group of campers for use at a site without facilities. So it could be just like you would have at home--a full size shower and bathtub, or even a jacuzzi, along with the normal toilet and sink wash station.